Fix feature flag information

One flag needs the inclusion of a flag box. One has been gone for
a long time, and needed its removal documented.

doc/ci/pipelines/merge_trains.md

@@ -156,6 +156,10 @@ You can also remove (**{close}**) a merge request from the merge train details v
 > - Auto-merge for merge trains [enabled](https://gitlab.com/gitlab-org/gitlab/-/issues/470667) on GitLab.com in GitLab 17.2.
 > - Auto-merge for merge trains [enabled](https://gitlab.com/gitlab-org/gitlab/-/issues/470667) by default in GitLab 17.4.
 
+FLAG:
+The availability of this feature is controlled by a feature flag.
+For more information, see the history.
+
 Prerequisites:
 
 - You must have [permissions](../../user/permissions.md) to merge or push to the target branch.

doc/integration/oauth_provider.md

@@ -140,10 +140,7 @@ application are also deleted.
 > - [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/374588) in GitLab 15.4 [with a flag](../administration/feature_flags.md) named `hash_oauth_secrets`. Disabled by default.
 > - [Enabled on GitLab.com](https://gitlab.com/gitlab-org/gitlab/-/issues/374588) in GitLab 15.8.
 > - [Enabled on self-managed](https://gitlab.com/gitlab-org/gitlab/-/issues/374588) in GitLab 15.9.
-
-FLAG:
-On self-managed GitLab, by default this feature is available. To hide the feature, an administrator can [disable the feature flag](../administration/feature_flags.md) named `hash_oauth_secrets`.
-On GitLab.com, this feature is available.
+> - [Generally available](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/113892) in GitLab 15.10. Feature flag `hash_oauth_secrets` removed.
 
 By default, GitLab stores OAuth application secrets in the database in hashed format. These secrets are only available to users immediately after creating OAuth applications. In
 earlier versions of GitLab, application secrets are stored as plain text in the database.